The field of this invention lies in the art of making oxyaluminum acylates for use in manufacturing aluminum complex greases.
Previously I have discovered that new oxyaluminum acylates can be prepared by utilizing three carboxylic acids: An aromatic acid, an aliphatic acid, and a lower alkanoic acid. The lower alkanoic acid, during the synthetic preparation procedure, produces, as explained in my application U.S. Ser. No. 096,933, an ester by-product which is easily volatilized and removed. This process can be used to prepare oxyaluminum acylate containing not more than about 75 mole percent of aromatic carboxylic acid, and oxyaluminum acylates so produced were found to be useful in the manufacture of aluminum complex grease of apparent commercial quality.
When such three acid route is used to prepare oxyaluminum acylates containing more than about 75 mole percent of an aromatic carboxylic acid, the product oxyaluminum acylates do not appear to be useful for the manufacture of aluminum complex greases of apparent commercial quality (by using, for example, the grease preparation procedure described in my application U.S. Ser. No. 096,933).
Oxyaluminum acylate synthesized by the three acid route tend to produce product acylates which are characteristically not clear when the product acylate contains more than about 75 mole percent of an aromatic carboxylic acid. In addition, such acylates are heterogeneous in composition and are not readily soluble in organic liquids of the type conventionally used for making greases. Furthermore, greases made with such product acylates are not uniform and characteristically contain opaque solid particles. It is theorized (but there is not intent herein to be bound by theory) that the three acid route results in the production of product oxyaluminum acylates which contain lower alkanoate substituents which cause such undesirable properties for grease making purposes, particularly when one is dealing with oxyaluminum acylates containing more than about 75 mole percent of aromatic carboxylic acid.
In addition, it has now been learned that even with the oxyaluminum acylates containing up to 75 mole percent of aromatic carboxylic acid as described in my application U.S. Ser. No. 096,933, certain disadvantages exist from the standpoint of making aluminum complex greases. For one thing, during grease manufacture by the methodology described in my application U.S. Ser. No. 096,933, an acrid odor occurs, which odor suggests acetic acid vapor, are given off. These vapors are considered undesirable by grease makers.
In addition, product greases made with such oxyaluminum acylates prepared by the three acid route tend to demonstrate so-called false set characteristics (that is, the grease demonstrates an ability to become relatively rigid on standing even after a brief period of time at ambient conditions). Even though agitation of a false set grease can result in lessened viscosity, in a manner comparable to common thixotropic systems, false set is generally considered undesirable in the grease industry in a product grease for some purposes, as when the grease is to be marketed in a cartridge for cartridge-gun application (a cartridge holding viscous grease may not be applicable from the gun).
Therefore, it would be desirable to have a process for preparing oxyaluminum acylates suitable for use in making aluminum complex greases of commercial quality which does not utilize the three acid route.